The invention relates to a percussion fuse with a rigidly mounted firing pin and an impact body disposed behind the firing pin which impact body includes a percussion cap. The impact member of the fuse is securely mounted by means of a blocking sphere until the projectile actually leaves the gun barrel muzzle, which blocking sphere engages in a transverse groove of the impact member and is mounted in a bore of the percussion fuse body. The arrangement further includes a movably mounted inertial sphere, and means for clamping this inertial sphere disposed between the impact member and the ignition head, which means clamps the inertial sphere between the impact member and ignition head at premature deceleration of the projectile.
There is disclosed in coassigned U.S. Pat. No. 4,036,145 a percussion fuse assembly which, in case of a premature deceleration of the projectile, clamps the inertial sphere movably arranged between the impact body and the ignition head between two conical surfaces of equal angularity. The first conical surface is rigidly joined to the ignition needle, whereas the second conical surface is disposed in the forward portion of the impact body which impinges on the ignition needle upon impact of the projectile.
A premature deceleration of the projectile can, for example, be caused by means of obstacles, which may be located in the immediate vicinity of the firing position. Such obstacles can take the form of tree branches and leaves, in particular when the firing position is camouflaged. As a result of the premature deceleration of the projectile the fail-safe operation is inhibited which, in the worst case, basis, can lead to the service personnel being placed in danger by means of a premature detonation of the projectile.
With the known percussion fuses, in which a freely movable inertial sphere is clamped between two conical surfaces at premature deceleration, there was not attained in all cases a sufficiently satisfactory fail-safe operation. This was attributed to the fact that, as a result of intense vibrations which occur during the firing and acceleration phase of the projectile, the inertial sphere could slide out of its clamped position and as a result could no longer prevent the initiation of an ignition process.